1. Field of the Invention
The invention relates to a panel, in particular a floor panel, with a core of wood material or a wood material/plastic mixture and a method of joining the floor panels and making the panels.
2. Discussion of Background Information
A panel is known, for example, from WO 2007/020088 A1. With the corresponding profile the horizontal locking and the vertical locking is achieved with elements separated from one another.
Floor panels are also known from WO 2004/003314 A1 which can be connected to one another and locked to one another by an essentially vertical joining movement. With these panels, the locking projection is formed by a vertical slot in a resilient manner and can yield in the horizontal direction during the locking operation. This type of locking is preferably provided on the transverse side of floor panels. However, it can also be provided on the longitudinal side or on the longitudinal side as well as on the transverse side.
In the case of the panel known from EP 1 650 375 A1, the tongue element is composed of plastic and is inserted in a groove running horizontally on one of the side edges and beveled on its top side. Similar to a door latch, by means of the bevel the locking element is pressed inwards into the groove by the panel to be newly set, when the underside of this panel meets the bevel and is further lowered. When the panel to be newly laid has been completely lowered to the subfloor, the tongue element snaps into a groove inserted horizontally in the opposite side edge and locks the two panels in the vertical direction. Special injection molding tools are required for the manufacture of this tongue element, so that the production is relatively expensive. Furthermore, a high-quality plastic has to be used to provide adequate strength values, which makes the tongue element even more expensive. If plastics with insufficient strength values are used, this leads to relatively large dimensions of the tongue elements, since this is the only way to ensure that corresponding forces can be produced or transferred.
The fact that the locking element is embodied as a separate component results in additional expenses. For technological reasons the production of the locking element takes place in a separate location from the panels, so that integration into the continuous production process, in particular for floor panels, is hardly possible. Because of the different materials, wood material on the one hand and plastic on the other hand, it is complex and cost-intensive to match the manufacturing tolerances from two separate production processes. Since the locking in the vertical direction would be ineffective if the locking element were missing, this element must further be secured from falling out of the groove introduced into the side edge during the further production process and during transport. This securing is also complex. As an alternative, the locking element could also be provided separately to the consumer.
The floor panels under consideration are being laid with increasing frequency by non-professionals (self-installers), so that in principle it is possible, due to a lack of experience, for the required number of locking elements to be initially miscalculated and not obtained in sufficient quantity in order to be able to lay a room completely. Furthermore, it cannot be ruled out that the self-installers make a mistake when placing the tongue element, which means that precise locking is not possible and the bond separates over time. This is then wrongly attributed by the consumer to the quality supplied by the manufacturer.
A panel is known from DE 102 24 540 A1, which is profiled on opposite side edges such that hook-shaped connection elements are formed for locking in the horizontal direction. For locking in the vertical direction, positive engagement elements spaced apart from one another horizontally and vertically are provided on the connection elements, and undercuts corresponding thereto are provided with respectively one horizontally aligned locking surface. The transverse extension of horizontally aligned locking surfaces of this type is approximately 0.05 to 1.0 mm. The dimensioning has to be very small in order for the joining of two panels to remain possible. However, this inevitably means that only low, vertically aligned forces can be absorbed, so that production must be carried out with extremely low tolerances in order to ensure that the connection does not spring open with normal stress in the case of even slight irregularities in the floor and/or soft subfloors.
A panel is described in DE 10 2007 015 048 A1 in which the locking in the vertical direction is carried out by a tongue element that is moveable in the horizontal direction. With a joining movement, the tongue element snaps in behind a locking edge extending essentially in the horizontal direction. The tongue element is formed by a horizontal and vertical cut from the core and connected to the core on at least one of its two ends. The horizontal and vertical cut render possible the spring movement of the tongue element necessary for producing the locking. However, this locking is not suitable for thinner panels with a board thickness of approximately 4 mm to 8 mm.
Based on this problem, the present invention overcomes these shortcomings and provides improvements to known panels.